magento customer creation and guest to be converted to regular customer

Im using magento 1.4.1.1 .Im using google checkout for the payment. I buy a product as Checkout as Guest instead of creating an account(logging as guest) . I give my email id as thomas@xyz.com in the billing ad开发者_C百科dress.Im able to buy the product. After few days i again signup as guest sinc ei first logged in as a guest with the given email id customer account ot be created and the previous and latest order need to be assigned to that customer. How i can do that ? Is there a plugin for that ?

It would be dangerous to allow newcomers to sign up and receive old customer's order details. Someone might fake an email address and effectively steal their identity. Instead you should disallow guest purchases so customers are forced to signup, or perhaps automatically sign up anyone who uses google checkout.